An analytical method, in which blood collected from a human body is analyzed as a test sample to diagnose human diseases, has conventionally been performed. The method is generally classified into two types, that is, a wet analytical method in which a reagent(s) necessary for designed analysis and a test sample are added into water to prepare a solution to allow some detectable reaction to take place; and a dry analytical method in which a test sample is supplied onto a layer (gelatin layer, for example) containing reagents previously in dry state to allow some detectable reaction to take place in the layer.
In the case where enzyme activity is measured by utilizing a dry analytical method, for example, such an analytical element is utilized that has one or more layers containing reagents in dry state on an undercoated transparent polyethylene terephthalate (PET) base and a spreading layer of tricot knitted cloth made of polyester spun yarn laminated on the layer.
The spreading layer plays an important roll to make a supplied test sample diffuse uniformly in lateral and longitudinal directions. In other word, uniform contact between a reagent and the test sample, which is achieved by stirring of a solution in the wet analytical method above described, is realized by the uniform diffusion of the test sample in the spreading layer.
Such dry analytical elements include a dry analytical element suitable for analyzing activity of lactate dehydrogenase (LDH) in a test sample. The analytical element contains lactic acid or salts thereof and nicotine amide coenzyme in an oxidized form (NAD+). By utilizing the analytical element, nicotine amide coenzyme in a reduced form (NADH) produced through reaction is detected with a coloring reagent and so on.
However, in the case of quantitative analysis of LDH in a test sample by utilizing such a dry analytical element, measured values sometimes fluctuate (shift to a higher value) depending on processing method of the test sample and some countermeasures for improvement have been desired.
On the other hand, in a wet analytical method, reaction is allowed to occur by mixing an aqueous solution dissolving a reagent(s) necessary for designed analysis and a blood test sample. In the wet analytical method also, measured results sometimes fluctuate depending on processing method of the test sample and some countermeasures for improvement have been desired.